In this case, and for a European, as myself, the problem isn't deciding the device to buy, is finding it.

The specs anybody just wanting to read would need is at least a 7'' screen and e-ink. If it could read epub, pdf and mobi decently it would be nice as well.

The kindle 9.7'' is a bit big and too expensive for what is worth. Thought of buying one used but could not find one (most are in the US and don't ship overseas).
Pocketbook pro902 has the same exact problems.
Nook color doesn't really fit on my requirements (color, battery life, no e-ink).
There are some fuzzy ones from iRex and velocity micro, but don't really know the brands and can't seem to find any good reviews.

The one that comes close enough is sony prs900, though also just a bit expensive for 7'' and the apparently crappy sipix screen.

The question is: wait 'til I can find a used kindle dx in good conditions(or until they lower the price - which isn't in the horizon...) or just buy a sony and end of the discussion?

Found a few used Kindle DX in Italy and France. I'll probably buy one of those. I'd prefer getting one from the states (with the conversion rates it would be cheaper, even with the shipping fees and VAT) but there's a slim chance of that happening so...

irex800s will suit your needs, if you can get hold of one.. it is great for reading all material, very clear screen and very usable... The downside is IREX went into administration last year, and I don't know what is happening with them right now.. Also when i purchased mine it was expensive...(450pounds i think) But as i read a lot of technical books that are in PDF the 6inch screens do not work well with PDFs and i was fed up with lugging my tech books around, this one has an 8.1 inch screen... so you may be able to find one out there cheaper than the Kindle DX, i believe there are some new ebook readers being released soon.

For me, if anything i would be tempted to go for a bigger screen next time for PDF viewing, but then you have the down side of the size of the screen to carry around..

irex dr800s can't be found anywhere, and without support I'm reluctant in considering it (even though it would be perfect for what I need).

USunlocked is great! Never knew something like that existed. Thanks! Sent them an email regarding customs charges.
Well, between DX and PRS 950 I'll get the one I can get cheaper.

EDIT: reading again the latest comment, it's probably the best solution going for the big screen, precisely because of the technical books in pdf. As I carry around a backpack all the time, the size of it won't be a problem, so there's go the downside...

Found a few used Kindle DX in Italy and France. I'll probably buy one of those. I'd prefer getting one from the states (with the conversion rates it would be cheaper, even with the shipping fees and VAT) but there's a slim chance of that happening so...

Thank you all anyway!

Cheers

You can purchase all products, that are available in the US, via services like USUnlocked.com.
As a rule of thumb: In Europe, you'll end up around the same amount in Euro, which the unit in the US originally had been in US Dollar.
Usually, you have to pay about 10% fee to the supplier, about $ 30 for shipment, plus customs/VAT.
A reader, which costs around $ 300 in the US, will end up in the range of 270 to 320 Euro.
Usually, that's not a big problem. If the respective reader is available in Europe later on, it will have more or less the same price.
Europe, on average, simply is around 25% more expensive than the US market.